Below are the percentages of votes from each party in five battleground states. (The analysis is from Catalist, a data company whose president is Harold Ickes, a former White House deputy chief of staff to President Bill Clinton.) Colorado is almost even, with the largest gap in Ohio:

Traditionally, more Republicans cast their ballots on Election Day, so the challenge for Democrats has been to encourage supporters to visit the polls early. Early voting was one of President Barack Obama's major themes on his swing-state campaign tours in the weeks leading up to the election.